Clues that pt may have anaerobic infection: the infection is at or near a site where anaerobes are normal flora, there is a foul-smelling discharge, no bacterial growth on routine aerobic cultures, gas is present, fails to improve on antibiotics that cover aerobic infections.

Superantigens: Polypeptide exotoxins that bind directly to class III MHC proteins and are able to turn on large numbers of T cells. This results in a massive release of IL-2 from T cells and TNF and IL-1 from macrophages which results in clinical fever, endothelial dysfunction and shock. Superantigens are produced by Group A Strep and S. aureus and other bacteria, viruses and fungi.

Infections are serious and include osteomyelitis (most common), meningitis, endocarditis.

Gram Negative Rods

Enteric gram negative rods: Some cause both GI and extra-intestinal dz, some only GI dz, some are part of normal intestinal flora but only cause extra-intestinal dz, can also be found in soil and water.

Saprophytic gram neg rods found in soil and water are not commonly part of GI normal flora.

Less Common Pathogenic: Bartonella, Capnocytophaga, Prevotella, HACEK group

Escherichia coli (E. coli)

Gram neg rod.

#1 cause of UTIs (community & nosocomial)

Etiologic agent of bacteremia, sepsis, neonatal meningitis

(Neonatal meningitis also caused by Group B strep and Listeria.)

Women at ↑ risk due to short urethra.

Anterior portion of urethra usually colonized.

Transmission via fecal contamination or catheter use.

Infecting strains originate from GI tract.

Virulence factors: include adhesins and exotoxins

↑ resistance to multiple antibiotics is problem.

Etiologic Agents of Gastroenteritis

E. coli 5 subdivisions

Enterotoxigenic

Enteropathogenic

Enteroadherent

Enterohemorrhagic

Enteroinvasive

Salmonella

Gram neg rod.

Can colonize nearly any animal (like campylobacter)

Animal reservoir mostly responsible for non-typhoid human dz.

Transmitted by ingestion of contaminated food; eggs, poultry, dairy

Large inoculum required for infection.

Salmonella typhi, S. choleraesuis, and S. paratyphi A and B are serotypes that only infect humans and are transmitted by fecal-oral route. Chronic carrier state common. Typhoid spp only need small inoculum for infection.

U. urealyticum: most common/most important, infants (esp. females) colonized with species of both Mycoplasma and Ureaplasma at birth but this disappears shortly afterward and then increases again in early adulthood.

Molluscum contagiosum: Pox virus, DNA virus, strictly human virus, lesions are pearl-like and umbilicated papules, spread by direct contact (including sexual), autoinoculation plays important role, sometimes itches, sometimes asymptomatic, goes away on own in 6mo, usually only few 6-12 lesions, responds to cryotherapy, adults can have this as an STD like genital warts

Chicken pox/shingles: VZV (lesions present in all stages at same time, showers of lesions every few hours)